Seismic Response of Ground Penetrating Shield Tunnels Under Lateral Harmonic Excitations: Insights From Shaking Table Test

The ground penetrating shield tunnel (GPST) method offers a streamlined approach to tunnel construction in soft ground with limited open-cut excavation. To explore the seismic response of GPST linings, a series of large-scale shaking table tests have been conducted, including a variety of seismic excitations. This paper focuses on lateral harmonic excitation. The model tunnel spans a total length of 7.7 m, with the embedment depth ranging from -0.5 to 0.5 times its diameter. The design and fabrication of the model tunnel are presented, including the segmental lining, along with circumferential and longitudinal joints. The soil was modeled with artificial synthetic soil, aiming to simulate the static and dynamic characteristics of the prototype soil. Its composition was adjusted and verified through element tests. The experimental results provide insights into the seismic response of the soil-tunnel system, the ovaling deformation of the segmental lining, as well as the response of the joints between lining segments. The results reveal a strong influence of embedment on tunnel seismic response. The reduction of tunnel embedment leads to a significant increase in lining accelerations and a phase difference, resulting in a "whiplash" effect. In contrast, the ovaling deformation of the lining and the joint apertures decrease with the reduction of embedment. In the sections of the tunnel that are fully embedded, both the acceleration and deformation response of the lining are governed by soil-structure interaction (SSI). A pronounced whiplash effect is observed in the sections of the tunnel that are not fully embedded, due to the absence of soil confinement. The presented experimental results offer valuable insights into the seismic response of GPSTs, which can be of crucial importance for their seismic design.